JP6187918B2 - Circuit member connection structure, connection method, and connection material - Google Patents

Description

  The present invention relates to a connection structure using a solder material between a circuit member having a transparent electrode and a circuit member having a metal electrode.

  Usually, a transparent circuit member such as a glass substrate includes a transparent electrode. For example, when a liquid crystal display substrate and a flexible substrate (FPC) are electrically connected, it is necessary to connect a metal electrode included in the FPC and a transparent electrode included in the liquid crystal display substrate. However, since the transparent electrode is difficult to get wet with the molten solder material, it is difficult to achieve a good connection state. Thus, a technique has been proposed in which a transparent electrode is coated with a highly wettable metal plating, and then the metal electrode and the transparent electrode are connected with a solder material (Patent Document 1).

  However, in order to cover the transparent electrode with metal plating, a corresponding increase in cost is required. On the other hand, a connection method between electrodes called Chipglass (COG) and Filmglass (FOG) using an anisotropic conductive film (ACF) instead of a solder material has been proposed (Patent Document 2).

JP 58-182684 A JP 2012-190804 A

  However, the conductive particles contained in the ACF are formed of resin particles and a conductive layer covering the surface. Such conductive particles achieve electrical contact with the electrodes by being compressed between the electrodes at a high pressure of 50 MPa to 150 MPa at a high temperature close to 200 ° C., for example.

  As described above, in the circuit members connected by the ACF, in addition to the expansion and contraction stress due to heat, considerable distortion due to the pressure during compression occurs. On the other hand, in a circuit member provided with a transparent electrode, since the substrate is becoming thinner, defects due to stress are becoming apparent.

  In addition, since the conductive particles contained in the ACF expand when exposed to a high temperature, the contact area with the electrode tends to decrease and the connection resistance tends to increase.

In view of the above, one aspect of the present invention provides a first circuit member having a first main surface provided with a transparent electrode, a second circuit member having a second main surface provided with a metal electrode, and the first main surface. And a joint portion interposed between the second main surface, the joint portion includes a resin portion and a solder portion, and the solder portion includes the transparent electrode and the metal electrode. Electrically connected, the transparent electrode includes an oxide including indium and tin, the solder portion includes a bismuth-indium alloy, and between the transparent electrode and the solder portion, The present invention relates to a circuit member connection structure including indium and bismuth and having a first alloy layer different from the solder portion .

Another aspect of the present invention is a circuit member connection for connecting a first circuit member having a first main surface with a transparent electrode and a second circuit member having a second main surface with a metal electrode. A method comprising: (i) preparing a connecting material including an adhesive and a solder material dispersed in the adhesive; and (ii) the transparent electrode and the metal electrode through the connecting material. A step of disposing the first circuit member and the second circuit member so as to face each other; and (iii) heating the second circuit member against the first circuit member while heating the solder material, (Iv) the step of forming a solder part for electrically connecting the transparent electrode and the metal electrode by stopping the heating and solidifying the molten solder material after melting By curing the adhesive, the first circuit member and the second circuit member Includes a step of forming a resin portion for wearing, wherein the transparent electrode comprises an oxide containing indium, and tin, wherein the solder material is bismuth - including indium alloy, wherein step (iv) In parallel with the step (iii) or after the step (iii), the indium contained in the transparent electrode is formed between the transparent electrode and the solder portion together with the formation of the solder portion. The present invention relates to a method for connecting circuit members , wherein a first alloy layer including bismuth contained in the solder portion is formed .

  According to the above aspect of the present invention, it is possible to provide a circuit member connection structure having small residual stress and excellent connection reliability.

It is a perspective view which shows the external appearance of the display panel which is an example of the electronic device which has the connection structure which concerns on this embodiment. It is sectional drawing of the principal part of the display panel. FIG. 3 is an enlarged view of a region surrounded by a broken line X in FIG. 2. It is an enlarged view of the section of another important section of the display panel. It is process drawing which shows an example of the connection method for manufacturing the connection structure which concerns on this embodiment. It is an electron micrograph of the area | region containing the glass part of a 1st circuit member, the solder part, and the metal electrode part of a 2nd circuit member in the connection structure of the circuit member produced in Example 1. FIG. It is an electron micrograph of the interface area | region (formation area | region of a 1st alloy layer) of a transparent electrode and a solder part. It is an electron micrograph of the interface area | region (formation area | region of a 2nd alloy layer) of a metal electrode and a solder part. It is a schematic diagram of the principal part of the connection structure of a transparent electrode, a solder part, and a metal electrode.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the following drawings are only examples and do not limit the present invention.
A circuit member connection structure according to an embodiment of the present invention includes: a first circuit member having a first main surface provided with a transparent electrode; a second circuit member having a second main surface provided with a metal electrode; A joining portion interposed between the main surface and the second main surface. The joining portion has a resin portion and a solder portion. The solder part electrically connects the transparent electrode and the metal electrode. Here, the transparent electrode includes an oxide containing indium (In) and tin (Sn). On the other hand, the solder portion contains bismuth (Bi) and indium.

  Although a 1st circuit member is not specifically limited, For example, it may be a transparent substrate used for the display panel with which a television, a tablet, a smart phone, a wearable device, etc. are equipped. The transparent substrate may be translucent. Examples of the transparent substrate include a glass substrate and a film-like substrate. The film substrate is formed of a transparent resin film. The resin film having transparency may be a film of polyethylene terephthalate (PET), polycarbonate (PC), polyethylene naphthalate (PEN), or the like. The first main surface may be any main surface of the first circuit member.

  The second circuit member is not particularly limited, and may be, for example, a semiconductor chip, an electronic component package, a film substrate, a connector, or the like. The second main surface can be any main surface of the second circuit member.

  The transparent electrode provided on the first main surface may be an oxide containing indium and tin, and may contain a trace amount of a third metal element other than indium and tin. A typical example of the transparent electrode is a so-called indium tin oxide or tin-doped indium oxide (Indium Tin Oxide (ITO)) electrode.

  Although the metal electrode provided in the 2nd main surface is not specifically limited, For example, it may be an electrode containing gold | metal | money, platinum, copper, nickel, palladium, various solders, etc. The solder forming the metal electrode can be, for example, a solder containing tin, silver, bismuth, indium, nickel, copper, and the like.

  The solder portion contains bismuth and indium. It is desirable that bismuth and indium form an alloy (bismuth-indium alloy). The solder portion may include a component other than the bismuth-indium alloy, for example, a third element that does not form the bismuth-indium alloy, and may include a region of bismuth alone and / or a region of simple indium. However, the amount of the bismuth-indium alloy contained in the solder part is preferably 97% by mass or more, more preferably 99% by mass or more, from the viewpoint of forming a homogeneous and highly reliable solder part having high strength. It is particularly preferable that the whole is formed of a bismuth-indium alloy.

  The bismuth-indium alloy may contain a trace amount of a third element other than bismuth and indium as an alloy component. However, the amount of the third element contained in the bismuth-indium alloy is desirably 1% by mass or less. That is, the solder portion is desirably formed by melting a bismuth-indium alloy (solder material) containing a total of 99% by mass or more of bismuth and indium and subsequent solidification.

  The portion containing the bismuth-indium alloy forming the circuit member connection structure is referred to as a solder portion, and the material containing the bismuth-indium alloy before forming the circuit member connection structure, that is, before melting between the electrodes. Is referred to as a solder material.

Between the transparent electrode and the solder section, that is formed first alloy layer comprising indium and bismuth. The first alloy layer is generally formed of indium contained in the transparent electrode and bismuth contained in the solder material forming the solder portion. The first alloy layer may include indium contained in the solder material. However, the first alloy layer is formed of an alloy different from the solder portion. Usually, since the composition and / or structure of the first alloy layer is different from the composition and / or structure of the solder part, the presence of the first alloy layer is determined by various analysis methods such as a scanning electron microscope and a transmission electron microscope. Etc. can be confirmed.

  On the other hand, a second alloy layer containing a metal component contained in the metal electrode and bismuth and / or indium contained in the solder material forming the solder portion is formed between the metal electrode and the solder portion. It is preferable that That is, the second alloy layer includes a metal component common to the metal component included in the metal electrode. For example, when the metal electrode contains three elements of copper, nickel and gold, the second alloy layer contains at least one selected from the group consisting of copper, nickel and gold.

  Since indium contained in the solder material is excellent in malleability, the wetted area between the solder material and the transparent electrode and the metal electrode can be increased. On the other hand, bismuth is an abnormal liquid whose volume expands when solidified from a molten state. Since the solder material contains bismuth, the pressure at the interface with the transparent electrode and the interface with the metal electrode is increased when the solder material is solidified, so that the reaction for forming the first alloy layer and the second alloy layer proceeds. It becomes easy.

  When using a solder material, an electrical connection between electrodes can be achieved at a lower pressure than when using an ACF. For example, the pressure required for connection between the electrodes may be 0.5 to 4 MPa. Bismuth and indium are both low melting point metals, and alloys containing these have lower melting points. Therefore, the temperature necessary for the connection between the electrodes may be low (for example, the melting point of the solder material + 10 ° C. or less). Therefore, the stress caused by the pressure and heat applied to the circuit member at the time of connection can be reduced. Thereby, even when a thin and low-strength circuit member is connected, a malfunction is unlikely to occur, and high reliability can be ensured. Further, by forming the first alloy layer and the second alloy layer, the contact area between the solder portion and each electrode hardly decreases even at high temperatures.

  The resin portion bonds the first main surface and the second main surface and covers at least a part of the solder portion. Thereby, a solder part is reinforced and the intensity | strength of a connection structure improves. In addition, even when the pitch between the electrodes is narrow, it is easy to ensure insulation between adjacent electrodes. For example, the resin part is desirably formed so as to fill in the gaps between the plurality of solder parts that connect the plurality of transparent electrodes and the plurality of metal electrodes.

  The resin part may contain various additives. Examples of the additive include an activator for removing a solder material and an oxide film on the electrode surface by heating, a filler, a curing agent for a resin component, and the like. The resin component is not particularly limited, and a thermosetting resin, a photocurable resin, a thermoplastic resin, or the like can be used. Of these, thermosetting resins are preferable, and epoxy resins and acrylic resins are particularly preferable.

The amount of bismuth contained in the bismuth-indium alloy contained in the solder portion is preferably 27% by mass to 68% by mass. Most of the balance of the bismuth-indium alloy (99% by mass or more of the balance) is preferably indium. Such a bismuth-indium alloy has high wettability and connection reliability with a transparent electrode, and has a low melting point. The bismuth-indium alloy contained in the solder portion includes, for example, at least one selected from the group consisting of BiIn ₂ , Bi ₃ In ₅ and BiIn.

  FIG. 1 is a perspective view showing an appearance of an example of a display panel. The display panel 100 in the illustrated example includes a glass substrate 200, a glass substrate 300, an image forming unit sandwiched between the glass substrate 200 and the glass substrate 300, a drive driver 400 that drives the image forming unit, and the display panel 100. And a connector 500 connected to other components. The drive driver 400 is mounted on the first main surface 200S that is one surface of the edge portion 200T provided at one end of the glass substrate 200 that is the first circuit member. Connector 500 is connected to another position on first main surface 200S. In the case of the display panel 100 in the illustrated example, both the drive driver 400 and the connector 500 correspond to the second circuit member.

  FIG. 2 shows a connection structure including a main part of the display panel 100, that is, a glass substrate 200 as a first circuit member, a drive driver 400 as a second circuit member, and a joint portion 600A interposed therebetween. It is a longitudinal cross-sectional view. FIG. 3 shows an enlarged view of a region surrounded by a broken line X in FIG. As shown in FIG. 2, a plurality of connection terminals 20 a that are transparent electrodes are formed on the first main surface 200 </ b> S of the glass substrate 200. On the other hand, the surface of the drive driver 400 facing the glass substrate 200 corresponds to the second main surface 400S.

  The plurality of connection terminals 20a are arranged on the first main surface 200S at a predetermined pitch. On the other hand, a plurality of bumps 40, which are metal electrodes, are arranged at the same pitch on the second main surface 400S. The plurality of bumps 40 of the drive driver 400 are aligned so as to face the plurality of connection terminals 20a. A joint 600A is interposed between the first main surface 200S and the second main surface 400S. As shown in FIG. 3, the joining portion 600A usually includes a resin portion 61a, a solder portion 62a, and a particulate solder material 63a.

  The solder part 62a is a part that contributes to the electrical connection between the connection terminal 20a and the bump 40, and is solidified in a wet state with the connection terminal 20a and the bump 40. As a result, a first alloy layer containing indium contained in the connection terminal 20a and bismuth contained in the solder material 63a is formed between the connection terminal 20a and the solder portion 62a. Yes. Further, a second alloy layer including a metal component contained in the bump 40 and bismuth and / or indium contained in the solder material 63a is formed between the bump 40 and the solder portion 62a. . On the other hand, the particulate solder material 63 a is irrelevant to the electrical connection between the connection terminal 20 a and the bump 40.

  The resin portion 61a serves to protect the solder portion 62a by bonding the first main surface 200S and the second main surface 400S and covering the solder portion 62a. In the illustrated example, a resin portion 61a is formed so as to fill a gap between both electrodes and the solder portion 62a.

  FIG. 4 shows a connection structure including another main part of the display panel 100, that is, a glass substrate 200 as a first circuit member, a connector 500 as a second circuit member, and a joint portion 600B interposed therebetween. It is an enlarged view of a longitudinal section. The connector 500 includes, for example, a flexible board formed of polyimide resin or the like, and a wiring pattern formed of copper alloy or the like on the board.

  On the first main surface 200S of the glass substrate 200, a plurality of connection terminals 20b, which are transparent electrodes, are arranged at a predetermined pitch. On the other hand, on the second main surface 500S of the connector 500 (the surface facing the glass substrate 200), a plurality of leads 50, which are metal electrodes, are arranged at the same pitch. The plurality of leads 50 are aligned so as to face the plurality of connection terminals 20b. A joint 600B is interposed between the first main surface 200S of the glass substrate 200 and the second main surface 500S of the connector 500.

  The joint portion 600B includes a resin portion 61b, a solder portion 62b, and a particulate solder material 63b, and each portion has the same structure as the joint portion 600A. Therefore, although not shown, a first alloy layer containing indium contained in the connection terminal 20b and bismuth contained in the solder material 63b is formed between the connection terminal 20b and the solder portion 62b. . Further, a second alloy layer including a metal component contained in the lead 50 and bismuth and / or indium contained in the solder material 63b is formed between the lead 50 and the solder portion 62b. .

Next, the connection method of the circuit member which concerns on embodiment of this invention is demonstrated.
The connection method is a method of connecting a first circuit member having a first main surface with a transparent electrode and a second circuit member having a second main surface with a metal electrode.
The connection method includes (i) a step of preparing a connection material including an adhesive and a solder material dispersed in the adhesive, and the solder material includes a bismuth-indium alloy.

  The adhesive is a raw material for the resin part, and is, for example, a resin composition containing a thermosetting resin, a photocurable resin, or a thermoplastic resin. As described above, the resin composition can contain an activator, a filler, a curing agent for the resin component, and the like. When a thermosetting resin is used, the curing temperature is not particularly limited, but is preferably higher than the melting point of the solder material. The curing of the thermosetting resin is desirably completed after the solder material is melted and the transparent electrode and the metal electrode are wetted by the solder material. The connection material may be a paste or a film.

  As an activator that reduces the surface of a transparent electrode or the like by heating, an organic acid, an organic acid salt of an amine, a halogen salt of an amine, or the like can be used. In these, since it has moderate activity, an organic acid is preferable. As the organic acid, adipic acid, abietic acid, sebacic acid, glutaric acid, 4-phenylbutyric acid, levulinic acid and the like can be used. One of these may be used alone, or two or more may be arbitrarily selected and used in combination.

  The bismuth-indium alloy contained in the solder material is, for example, in the form of particles. The size of the bismuth-indium alloy particles (hereinafter referred to as alloy particles) is selected from the viewpoint of ensuring electrical continuity between the corresponding transparent electrode and metal electrode and ensuring insulation between adjacent electrodes. As an example, the size (maximum diameter) of the alloy particles is desirably 1/5 or less of the electrode width, and more desirably 1/10 or less. The solder material may contain components other than the bismuth-indium alloy, but 95% by mass or more is preferably a bismuth-indium alloy, and 98% by mass or more is more preferably a bismuth-indium alloy.

  The bismuth-indium alloy contained in the solder material preferably has a melting point (mp) of 72 ° C. to 109 ° C., more preferably 85 ° C. to 109 ° C., and particularly preferably 88 ° C. to 90 ° C. preferable. Thereby, the connection between electrodes can be performed at a low temperature of, for example, 110 ° C. or less, desirably 100 ° C. or less. Therefore, the stress due to heat remaining on the circuit member can be remarkably reduced.

  Examples of bismuth-indium alloys having a melting point of 72 ° C. to 109 ° C. include, for example, 35Bi-65In (mp: 72 ° C.), 51Bi-49In (mp: 85 ° C.), 55Bi-45In (mp: 89 ° C.), 27Bi-73In (mp : 100 ° C), 68Bi-32In (mp: 109 ° C), and the like. However, XBi-YIn means an alloy containing X mass% bismuth and Y mass% indium.

  Further, from the viewpoint of improving the reliability of electrical connection, in the bismuth-indium alloy contained in the solder material, the amount of indium contained in the bismuth-indium alloy is preferably 32% by mass to 73% by mass, and 32% by mass to 49 mass% is still more preferable and 43 mass%-47 mass% are especially preferable.

  In the connection material including the adhesive and the solder material, the amount of the solder material may be, for example, 5% by mass to 80% by mass. By setting the amount of the solder material in the above range, it becomes easy to achieve both high connection reliability between the transparent electrode and the metal electrode and reliable securing of insulation between adjacent electrodes.

  Next, the connection method includes (ii) a step of arranging the first circuit member and the second circuit member so that the transparent electrode and the metal electrode face each other with the connection material interposed therebetween. However, the transparent electrode includes an oxide containing indium and tin.

  For example, the connection material is disposed in a region (hereinafter referred to as a first connection region) that covers at least a part of the transparent electrode on the first main surface of the first circuit member. If the connection material is a paste containing an uncured or semi-cured thermosetting resin or an uncured photo-curing resin, the connection material is applied to the first connection region using a printing device, a dispenser, an inkjet nozzle, or the like. do it. If the connection material is in the form of a film or tape, the film cut into a predetermined shape from the substrate may be peeled off and crimped to the first connection region. Such an operation is performed by, for example, a known tape attaching device. Note that the connection material may be disposed in a region (second connection region) covering at least a part of the metal electrode on the second main surface of the second circuit member, and disposed in both the first and second connection regions. May be. Thereby, a laminated structure in which the first circuit member and the second circuit member are arranged to face each other is obtained.

  FIG. 5A to FIG. 5B show an example of a state in which the connection material 600 </ b> P is disposed in the first connection region of the first circuit member 200 provided with the transparent electrode 20. FIG. 5C shows an example of a state in which the second circuit member 400 (500) is arranged on the first circuit member 200 through the connection material 600P. In the illustrated example, the second circuit member 400 (500) held by the suction tool 700 is mounted on the first circuit member 200. At this time, alignment is performed so that the transparent electrode 20 and the metal electrode 40 (50) face each other.

  When the adhesive contains a thermosetting resin, temporary bonding may be performed by heating the connection material 600P for a short time when the first circuit member and the second circuit member are arranged to face each other. Thereby, position shift with the 1st circuit member and the 2nd circuit member can be prevented. Temporary crimping is such that the solder material is not melted and the adhesive is slightly cured through the second circuit member (or the first circuit member) by the suction tool 700 having heating means such as a heater, for example. Heating may be performed on the connection material 600P.

  The pressure which presses the 1st circuit member and / or the 2nd circuit member in the case of temporary pressure bonding should just be 0.5-1.0 MPa, for example. Temporary press-bonding time may be about 0.1 to 1 second, for example. The temperature of temporary press-bonding may be, for example, 10 ° C. or lower than the melting point of the solder material.

  Next, in the above connection method, (iii) a step of heating the second circuit member against the first circuit member while heating it to melt the solder material is performed. Thereafter, heating is stopped and the molten solder material is solidified. Thereby, the solder part which electrically connects a transparent electrode and a metal electrode is formed. When the second circuit member is pressed against the first circuit member, the first circuit member is also pressed against the second circuit member. In other words, a pressing tool may be pressed against either circuit member.

  The step (iii) is a so-called thermocompression bonding step. The temperature for heating the first circuit member and / or the second circuit member at the time of thermocompression bonding may be not less than the melting point of the solder material included in the connection material, and may be a temperature not less than the melting point and not more than the melting point + 10 ° C. . For example, if the melting point of the bismuth-indium alloy contained in the solder material is 88 ° C to 90 ° C, the heating temperature may be 90 ° C or higher and 100 ° C or lower. Thereby, compared with the case where ACF is used, heating temperature can be reduced drastically.

  During thermocompression bonding, the pressure for pressing the first circuit member and / or the second circuit member may be 0.5 to 4 MPa, and preferably about 1 to 2 MPa. This is because, since the solder material is melted, electrical connection can be easily ensured by wetting between the electrode and the solder material without applying a very high pressure to the circuit member. Thereby, compared with the case where ACF is used, the pressure applied to a circuit member can be reduced dramatically.

  The time for thermocompression bonding is not particularly limited, but is preferably about 0.5 to 10 seconds, and more preferably about 1 to 5 seconds from the viewpoint of manufacturing cost.

  FIG. 5D shows an example of a state in which the first circuit member 200 and the second circuit member 400 (500) are thermocompression bonded. Here, the case where thermocompression bonding is performed on the stage 900 by the thermocompression bonding tool 800 is shown. Then, heating is stopped by separating the thermocompression bonding tool 800 from the second circuit member 400 (500), the solder is solidified, and a solder portion that electrically connects the transparent electrode 40 and the metal electrode 50 is formed. .

  During the thermocompression bonding, the reaction between indium contained in the transparent electrode and bismuth contained in the solder material proceeds at the interface between the transparent electrode and the solder material, and a first alloy layer is formed. . The first alloy layer is common to the solder portion in that it contains bismuth and indium. On the other hand, the first alloy layer includes an alloy different from the solder part, and this alloy has a composition and / or structure different from that of the solder part, for example. Usually, it is considered that the reaction between the transparent electrode and the solder material hardly proceeds. However, when a bismuth-indium alloy having a low melting point is used as a solder material as described above, a first alloy layer is formed. The presence of the first alloy layer can be confirmed visually by enlarging the cross section of the interface between the solder portion and the transparent electrode.

  Similarly, at the interface between the metal electrode and the solder material, the reaction between the metal component contained in the metal electrode and bismuth and / or indium contained in the solder material proceeds to form a second alloy layer. The The presence of the second alloy layer can also be confirmed visually by enlarging the cross section of the interface between the solder part and the metal electrode.

  In the above connection method, (iv) a step of curing the adhesive to form a resin portion that bonds the first circuit member and the second circuit member is performed. Step (iv) can also be performed in parallel with the thermocompression bonding in step (iii). For example, when the adhesive contains a thermosetting resin, the thermosetting resin can be allowed to cure by proceeding with the curing reaction of the thermosetting resin during thermocompression bonding. At this time, after curing, after-curing may be performed. When the adhesive contains a thermoplastic resin, the thermoplastic resin is melted during thermocompression bonding and welded to the first main surface of the first circuit member and the second main surface of the second circuit member. Thereafter, it may be solidified (cured). Further, when the adhesive contains a photocurable resin, for example, the adhesive may be irradiated with electromagnetic waves or light from the transparent first circuit member side. However, it is desirable that the irradiation with electromagnetic waves or light be performed after the solder material is melted. In the above case, a joint portion having a resin portion and a solder portion is formed by the end of thermocompression bonding.

  If the bonding between the first circuit member and the second circuit member does not proceed in parallel with the thermocompression bonding in the step (iii), the adhesive together with the first circuit member and the second circuit member after the step (iii). May be heated, or the adhesive may be irradiated with electromagnetic waves or light from the first circuit member side to complete the adhesion between the first circuit member and the second circuit member.

Next, the present invention will be described more specifically based on examples. However, the present invention is not limited to the following examples.
Example 1
(Connection material)
As a solder material, alloy particles of a bismuth-indium alloy (55Bi-45In (mp: 89 ° C.)) were prepared. The average particle size of the alloy particles was 3 μm, and the maximum particle size was 5 μm. On the other hand, a thermosetting resin composition containing 150 parts by mass of a bisphenol A type epoxy resin, 25 parts by mass of imidazole as a curing agent, and 20 parts by mass of adipic acid as an activator was prepared as an adhesive. The composition of the thermosetting resin composition was blended so as to be rapidly cured when heated to 80 ° C. or higher. Next, 20 parts by mass of alloy particles were dispersed in 100 parts by mass of the thermosetting resin composition to prepare a paste-like connection material.

(First circuit member)
A plurality of ITO electrodes (thickness: 1500 mm) having a width of 50 μm were formed as stripes on one surface (first main surface) of a glass substrate having a thickness of 0.3 mm and a rectangle (30 mm × 30 mm size). . The pitch of the ITO electrodes was 0.1 mm.

(Second circuit member)
A film substrate (FPC) made of polyimide resin having a thickness of 32 μm and a rectangle (16 mm × 35 mm size) was prepared. On one surface (second main surface) of the FPC, a plurality of metal electrodes (height 15 μm) having a width of 50 μm corresponding to the transparent electrodes were formed. The metal electrode is obtained by sequentially performing nickel (Ni) plating containing phosphorus and gold (Au) plating on the surface of a copper (Cu) base electrode.

(Connection of circuit members by thermocompression bonding)
A connection material was printed to a thickness of 30 μm using a printing device on the first connection region where the ITO electrode on the first main surface of the first circuit member was formed. Thereafter, the second connection region in which the metal electrode of the second circuit member is formed is opposed to the first connection region having the ITO electrode through the coating film of the connection material, and the first circuit member and the second circuit A laminated structure with the member was obtained.

  Next, using a thermocompression bonding tool having a flat surface, while pressing the second circuit member against the first circuit member at a pressure of 1.0 MPa, heating at 100 ° C. for 10 seconds to melt the solder material At the same time, the adhesive (thermosetting resin composition) was cured. Then, heating was stopped, the solder material was solidified, and the solder part which electrically connects a transparent electrode and a metal electrode was formed. Thus, a connection structure (sample structure) between the first circuit member and the second circuit member was completed.

[Evaluation]
The sample structure was cut in a cross section including a transparent electrode, a solder portion, and a metal electrode in parallel with the stacking direction, and the cross section was scanned with an electron microscope (SEM: manufactured by Hitachi High-Technologies Corporation, product number SU-70). ). In FIG. 6, the electron micrograph of the area | region containing the glass substrate of a 1st circuit member, a solder part, and the metal electrode of a 2nd circuit member is shown. FIG. 7 shows an enlarged photograph of the interface region between the transparent electrode and the solder portion (region where the first alloy layer is formed). In FIG. 8, the enlarged photograph of the interface area | region (formation area | region of a 2nd alloy layer) of a metal electrode and a solder part is shown. On the other hand, in FIG. 9, the principal part of the connection structure of a transparent electrode, a solder part, and a metal electrode is shown with a schematic diagram.

  In FIG. 6, it is difficult to clearly recognize the thin transparent electrode. However, it can be clearly understood that the solder portion is interposed between the glass substrate of the first circuit member and the metal electrode of the second circuit member to connect them.

  FIG. 7 is an image of the interface region between the transparent electrode (ITO electrode) and the solder portion with a higher magnification than that in FIG. 6, and the presence of the ITO electrode can be confirmed. In addition, it can be recognized that the first alloy layer containing Bi and In is formed at the interface between the ITO electrode and the solder portion.

  FIG. 8 is an image of the interface region between the metal electrode and the solder part at a higher magnification than that in FIG. 6, and the second alloy layer containing Bi, In, and Au is formed at the interface between the metal electrode and the solder part. It can be recognized that

  From the above, it was confirmed that the cross section of the connection structure had a multilayer structure as shown in FIG. That is, a first alloy layer is formed between the ITO electrode and the solder part, and a second alloy layer is formed between the metal electrode and the solder part. Thereby, even under high temperature, it is considered that the contact area between the ITO electrode and the solder part and / or the contact area between the metal electrode and the solder part does not decrease. Further, since thermocompression bonding is performed at 100 ° C. for 10 seconds at a pressure of 1.0 MPa, the residual stress of the connection structure is small. Therefore, even when a thin glass substrate is used, it is considered that problems such as when using ACF are unlikely to occur.

  The circuit member connection structure, connection method, and connection material of the present invention are useful as an alternative technique of the technique using ACF, and can achieve the connection structure at lower pressure and lower temperature. Therefore, it is particularly useful when forming a connection structure including a circuit member with low mechanical strength, such as a thin glass substrate, for example, when manufacturing a small liquid crystal included in a tablet, a smartphone, or the like.

20: Transparent electrode (connection terminal), 40: Metal electrode (bump), 50: Metal electrode (lead), 61a, 61b: Resin part, 62a, 62b: Solder part, 63a, 63b: Solder material, 100: Display panel , 200: first circuit member (glass substrate), 200T: edge, 200S: first main surface, 300: display control unit, 400: second circuit member (driving device), 400S: second main surface, 500: Second circuit member (connector), 500S: second main surface, 600A, 600B: joint, 600P: connection material, 700: adsorption tool, 800: thermocompression tool, 900: stage

Claims (22)

A first circuit member having a first major surface with a transparent electrode;
A second circuit member having a second major surface with a metal electrode;
A joint portion interposed between the first main surface and the second main surface,
The joint has a resin part and a solder part,
The solder part electrically connects the transparent electrode and the metal electrode,
The transparent electrode includes an oxide containing indium and tin,
The solder portion includes a bismuth-indium alloy,
A circuit member connection structure including indium and bismuth between the transparent electrode and the solder portion, and having a first alloy layer different from the solder portion . The circuit member connection structure according to claim 1 , wherein the resin portion adheres the first main surface and the second main surface and covers at least a part of the solder portion.   The circuit member connection structure according to claim 1 or 2, wherein a total amount of bismuth and indium contained in the solder portion is 97 mass% or more. The circuit member connection structure according to any one of claims 1 to 3, wherein an amount of indium contained in the bismuth-indium alloy is 32 mass% to 73 mass%. The bismuth - indium _alloy, BiIn _{2, Bi} 3 In ₅ and BiIn comprises at least one member selected from the group consisting of, a circuit member connection structure according to any one of claims 1-4. The solder portion has a melting point 72 ° C. to 109 ° C. bismuth - is one formed by a solder material containing indium alloy, a circuit member connection structure according to any one of claims 1-5. The circuit member connection structure according to any one of claims 1 to 5 , wherein the solder portion is formed of a solder material containing a bismuth-indium alloy having a melting point of 85C to 109C. The circuit member connection structure according to any one of claims 1 to 5 , wherein the solder portion is formed of a solder material containing a bismuth-indium alloy having a melting point of 88C to 90C. A first circuit member having a first major surface with a transparent electrode;
A second circuit member having a second major surface with a metal electrode;
A joint portion interposed between the first main surface and the second main surface,
The joint has a resin part and a solder part,
The solder part electrically connects the transparent electrode and the metal electrode,
The transparent electrode includes an oxide containing indium and tin,
The solder portion includes a bismuth-indium alloy,
Between the transparent electrode and the solder part, including indium and bismuth, having a first alloy layer different from the solder part,
The connection structure of a circuit member which has the 2nd alloy layer containing the metal component and common metal component which are contained in the said metal electrode, and bismuth and / or indium between the said metal electrode and the said solder part .   The metal electrode comprises gold;
  The second alloy layer includes bismuth, indium, and gold,
  The circuit member connection structure according to claim 9, wherein the second alloy layer includes unevenness at an interface with the solder portion. A first circuit member having a first major surface with a transparent electrode;
A circuit member connection method for connecting a second circuit member having a second main surface with a metal electrode,
(I) preparing a connection material including an adhesive and a solder material dispersed in the adhesive;
(Ii) disposing the first circuit member and the second circuit member so that the transparent electrode and the metal electrode face each other with the connection material interposed therebetween;
(Iii) by heating the second circuit member while pressing against the first circuit member to melt the solder material, and then stopping the heating to solidify the molten solder material Forming a solder portion for electrically connecting the transparent electrode and the metal electrode;
(Iv) curing the adhesive to form a resin portion that adheres the first circuit member and the second circuit member;
The transparent electrode includes an oxide including indium and tin, and the solder material includes a bismuth-indium alloy,
The step (iv) is performed in parallel with the step (iii) or after the step (iii).
Along with the formation of the solder part,
A method for connecting circuit members , wherein a first alloy layer including indium contained in the transparent electrode and bismuth contained in the solder portion is formed between the transparent electrode and the solder portion .   The circuit member connection method according to claim 11, wherein the total amount of bismuth and indium contained in the solder material is 95% by mass or more. The method for connecting circuit members according to claim 11 or 12 , wherein the solder material contains a bismuth-indium alloy having a melting point of 72C to 109C. The method for connecting circuit members according to claim 11 or 12 , wherein the solder material contains a bismuth-indium alloy having a melting point of 85C to 109C. The method for connecting circuit members according to claim 11 or 12 , wherein the solder material contains a bismuth-indium alloy having a melting point of 88C to 90C.   The method for connecting circuit members according to claim 11 or 12, wherein the amount of indium contained in the bismuth-indium alloy is 32 mass% to 73 mass%. Before SL Bismuth - amount of indium included in the indium alloy, 32% by mass to 49% by weight, the connection method of the circuit member according to claim 11 or 12. Before SL Bismuth - amount of indium included in the indium alloy, 43% by mass to 47% by weight, the connection method of the circuit member according to claim 11 or 12. The adhesive comprises an active agent;
The circuit member connection method according to any one of claims 11 to 18, wherein the activator reduces the surface of the transparent electrode by heating. The circuit member connection method according to claim 19 , wherein the activator includes at least one selected from the group consisting of adipic acid, abietic acid, sebacic acid, glutaric acid, 4-phenylbutyric acid, and levulinic acid. A first circuit member having a first major surface with a transparent electrode;
  A circuit member connection method for connecting a second circuit member having a second main surface with a metal electrode,
  (I) preparing a connection material including an adhesive and a solder material dispersed in the adhesive;
  (Ii) disposing the first circuit member and the second circuit member so that the transparent electrode and the metal electrode face each other with the connection material interposed therebetween;
  (Iii) by heating the second circuit member while pressing against the first circuit member to melt the solder material, and then stopping the heating to solidify the molten solder material Forming a solder portion for electrically connecting the transparent electrode and the metal electrode;
  (Iv) curing the adhesive to form a resin portion that adheres the first circuit member and the second circuit member;
  The transparent electrode includes an oxide including indium and tin, and the solder material includes a bismuth-indium alloy,
  The step (iv) is performed in parallel with the step (iii) or after the step (iii).
  Along with the formation of the solder part,
  Forming a first alloy layer containing indium contained in the transparent electrode and bismuth contained in the solder portion between the transparent electrode and the solder portion;
  A method for connecting circuit members, wherein a second alloy layer including a metal component contained in the metal electrode and bismuth and / or indium contained in the solder portion is formed between the metal electrode and the solder portion. .   The metal electrode comprises gold;
  The second alloy layer includes bismuth, indium, and gold,
  The circuit member connection method according to claim 21, wherein the second alloy layer includes irregularities at an interface with the solder portion.